Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
  • F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
  • F04C23/003—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle having complementary function
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C1/00—Rotary-piston machines or engines
  • F01C1/02—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
  • F01C1/0207—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
  • F01C1/0215—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C1/00—Rotary-piston machines or engines
  • F01C1/02—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
  • F01C1/0207—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
  • F01C1/0246—Details concerning the involute wraps or their base, e.g. geometry
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C17/00—Arrangements for drive of co-operating members, e.g. for rotary piston and casing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C17/00—Arrangements for drive of co-operating members, e.g. for rotary piston and casing
  • F01C17/06—Arrangements for drive of co-operating members, e.g. for rotary piston and casing using cranks, universal joints or similar elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C20/00—Control of, monitoring of, or safety arrangements for, machines or engines
  • F01C20/08—Control of, monitoring of, or safety arrangements for, machines or engines characterised by varying the rotational speed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C21/00—Component parts, details or accessories not provided for in groups F01C1/00 - F01C20/00
  • F01C21/02—Arrangements of bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2220/00—Application
  • F04C2220/22—Application for very low temperatures, i.e. cryogenic
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
  • F05B2260/00—Function
  • F05B2260/10—Particular cycles
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
  • F05C2251/00—Material properties
  • F05C2251/04—Thermal properties
  • F05C2251/042—Expansivity
  • F05C2251/044—Expansivity similar

Definitions

• the invention relates to the field of cryogenic expansion machines.
• cryogenic refrigeration gas cycles can be classified into two categories according to whether the process considered implements either a periodic circulation back and forth, or a permanent circulation in a defined direction of the gas.
• the gas exchanges heat with a thermal accumulator or a heat regenerator which retains heat when the gas circulates in one direction, and releases it when returning in the opposite direction.
• the best known alternative circulation cycles are the Stirling, Gifford Mac Manon, or the pulsation tube cycle.
• the latter is generally reserved for the production of low cooling powers of the order of a fraction of a watt around 4 Kelvin, around ten watts around 15 Kelvin, and around a hundred watts around 80 Kelvin.
• Figure IA shows a Stirling machine.
• a compressor 1 or pressure oscillator consists of a piston actuated mechanically by a crankshaft 2.
• the Gifford and Mac Mahon machine illustrated in FIG. 1B, is characterized by a gas compressor 3 with an inlet 4 at low pressure and an outlet 5 at high pressure, permanent and connected to the machine refrigeration proper 10 by an inlet valve 6 and an outlet valve 7 respectively, which are opened in turn to generate the necessary pressure cycles.
• the refrigerating machine 10, which is connected to these compressors 1 and 3 is the same in both cases. It consists of a tube 9 in which slides a displacement piston 11 which divides the contents of the tube 9 into two chambers with variable volume, connected together by a bypass 12, on which a heat regenerator 13 is installed.
• the chamber connected to compressor 1 or 3 is at temperature T2 (corresponding to the hot source), and the other chamber is at temperature T3 from the cold source.
• the displacer piston 11 passes the compressed gas from the chamber at temperature T2 to the chamber at temperature T3, by exchanging its heat with the heat regenerator 13 in response to the pressure increases in the compressor.
• the expansion of the gas is produced when it mainly occupies the room at temperature T3, then the gas is reheated by passing through the heat regenerator 13 towards the room at temperature T2 before undergoing a new cycle.
• the heat regenerator 13 has the property of restoring to the gas flowing there in one direction the heat which it previously took from the gas flowing in the opposite direction.
• the temperature chamber T2 communicates with the compressor 3 by the inlet 4 and the outlet 5; in the embodiments of FIG. IA, the connection of the compressor 1 to the compressor chamber at the temperature T2 is carried out by a single pressure tapping pipe 15.
• the machines thus alternative are the seat of two periodic waves in the volume of trigger 15, one of pressure and the other of flow. It is possible to control the phase shift of these two waves by mechanical means which control the movements of the compressor piston 1 or of the valves 6 and 7, generally at ambient temperature, and of the displacing piston 11 which can, for applications in cryogenics, have to operate at very low temperatures. We then effectively arrive at the desired situation where the maximum expansion, that is to say the maximum heat absorption, is simultaneous with the maximum gas flow rate in the cold source T3.
• FIG. 1C illustrates a pulse tube machine. It comprises a pressure oscillator 16, symbolized by a mechanical compressor, a heat regenerator 17 connected to the compressor 16 by a pressure tapping pipe 18 and a pulsation tube 19 which branches at the end of the heat regenerator 17 opposite to the pressure oscillator 16.
• the pulsation tube 19 is closed at the end opposite to the heat regenerator 17.
• the pulsation tube 19 is throttled near the heat regenerator 17, where the cold source SF is located, while the hot source SC is located at the opposite end of the pulsation tube 19, at the end of a portion enlarged and for example cylindrical thereof.
• the gas column is set in sustained oscillations, and the dimensions and the shape of the various elements of the apparatus make it possible to choose the operating frequency to obtain the phase shift of the flow waves and of pressure which effectively extracts heat from the cold source, to transfer it to the hot source.
• FIGS. 2A and 2B Such machines, operating on the principle of the Brayton cycle and the Claude cycle are respectively illustrated in FIGS. 2A and 2B.
• a compressor 20 recycles the gas from the low pressure level (BP), usually close to atmospheric pressure, to the high pressure level, generally between approximately 15 and 30 bars, one or more heat exchangers 22 against -current ensure the precooling of the compressed gas by exchange with the gas at low pressure,
• BP low pressure level
• high pressure level generally between approximately 15 and 30 bars
• one or more expansion machines 23 are the real source (s) of refrigeration production. We use either machines 23 in which the gas provides mechanical work, or simple throttles or expansion valves 24 where the gas undergoes a pressure drop.
• the Brayton cycle ( Figure 2A) can operate with nitrogen if the desired cold source
• the cycle gas 25 is at a temperature above 80 Kelvin.
• the cycle gas will generally be helium.
• the Claude cycle of FIG. 2A rather corresponds to a helium cycle, the cold source 26 of which is a bath of liquid helium.
• the expansion machines capable of producing work apply the first principle of thermodynamics according to which the sum of the quantities of heat Q and of work W brought into play in a cycle of reversible transformations is zero:
• An expansion without work or at constant enthalpy does not absorb heat, but it is generally used in the immediate vicinity of the saturation curve of the fluid to effect the phase change by expansion of the gas which is partially liquefied.
• the expansion turbines must rotate at high speeds, of several tens or hundreds of thousands of revolutions per minute, and are generally supported by non-contact bearings, most often gas.
• the piston regulators are, a priori, better adapted than the turbines to treat reduced flows, but their reliability is strongly conditioned by the achievement of the friction sealing between piston and cylinder, and by the existence of cold valves with the mechanisms associated command.
• the object of the invention relates to an original solution making it possible to produce machines for cooling fluid by expansion, in particular cryogenic (either isentropic or, if necessary, isothermal) better suited than turbines and piston machines for treating small flows with good efficiency, and good reliability, while being insensitive to the presence of liquid or fluid in double phase.
• cryogenic either isentropic or, if necessary, isothermal
• the subject of the invention is a device for lowering the temperature of a fluid by expansion of the fluid, in the gaseous or liquid state or in double phase, characterized in that it comprises an expansion compartment comprising:
• the invention uses moving parts without contact and without the use of valves.
• This device is compatible with miniaturization to treat low flow rates.
• it can accept, without any problem, the formation of two-phase fluid during expansion.
• It can, moreover, include in one of the spirals at least one heat exchange circuit making it possible to tend towards isothermal conditions.
• the means allowing circular translational movement, without proper rotation can take various forms. They can for example include:
• means can be provided to control the speed of rotation of the movable spiral during its movement.
• the movable spiral can be linked to a part around which an eccentric sleeve is rotating, a part linked to the eccentric sleeve being able to support the rotor of an electric brake.
• the rotation of this socket can be done with, on at least one of its two faces, a contactless bearing, of the magnetic or gas type.
• the spirals can be, for example, Archimedes' spirals where defined by a succession of arcs of a circle.
• a fluid expansion system can comprise at least two expansion stages, each comprising a device according to one of the forms described above.
• a common shaft may possibly allow a phase movement of the movable spirals of the various expansion devices.
• a cryogenic expansion machine can therefore include a compressor, an exchanger and an expansion device or system as described above. Brief description of the figures •
• FIG. 1A to 1C respectively illustrate Stirling, Gifford and pulsation tube machines
• FIGS. 2A and 2B illustrate machines of Brayton and Claude
• FIGS. 3A to 3D illustrate the operating principle of an expansion compartment of a device according to the invention
• FIG. 3E represents an embodiment with 4 spirals
• FIGS. 4A to 4C represent a sectional view of an expansion compartment of an either adiabatic or isothermal device according to the invention
• FIG. 5 represents a first embodiment of the invention
• FIGS. 6 to 9 show other embodiments of the invention.
• FIG. 10 shows a three-stage regulator according to the invention.
• FIGS. 3A to 3D and 4A Detailed description of embodiments The principle of the invention is based on the use of an expansion compartment comprising, as illustrated in FIGS. 3A to 3D and 4A, a first fixed spiral 28 and a second spiral 30 arranged movable at the inside the first. Each spiral rests or is linked to a flat bottom 32, 34.
• the gas to be expanded is introduced through an intake tube 36.
• An exhaust can be provided.
• reduced clearances 40, 42, provided between the upper part of the partitions 28, 30 of the spirals and the flat bottoms 32, 34 allow the fluid to escape outside the movable spiral, then the fixed spiral ( arrow referenced 44 in Figure 4).
• the gas can only circulate by increasing volume (expansion) and by exerting a force on the movable wall 30 (work), subjected to a circular translational movement. As a result of this movement, each point of the spiral 30 describes a circle, the movable part remaining permanently parallel to itself.
• FIGS. 3A to 3D illustrate the progress of the expansion of the gas in different stages, by which it is possible to follow the evolution of a fraction of the gas, from quarter to quarter to quarter of a turn.
• This gas passes through the continuously increasing volumes 46, 48, 50, 52, then finally 54, before exhaust.
• the volume of the gas during expansion is at all times limited by a partition of the fixed spiral and a partition of the movable spiral, which become tangent every 180 degrees, following their development.
• the spiral profiles may be Archimedes' spirals (the radius R of such a spiral varies linearly with the angle from the same center (R ⁇ a ⁇ )),
• the profiles can be defined by a succession of arcs of a circle, of different centers and of different radii, either for example at each half-turn, or again at each quarter-turn.
• FIG. 3E An exemplary embodiment with several spirals is illustrated in FIG. 3E.
• Two fixed spirals 27 and 29 are arranged symmetrical, at 180 ° relative to an axis of symmetry ⁇ .
• Two mobile spirals 31 and 33 become tangent alternately on one side with the spiral 27 and on the other side with the spiral 29.
• the thicknesses of the partitions of the spirals can be chosen constant or variable to optimize their mechanical strength and their size.
• the materials that can be used will preferably satisfy the condition that the two parts (fixed and mobile) are compatible, from the point of view of their expansion, so that the reduced clearances are obtained at nominal operating conditions at low temperature.
• materials with low expansion such as composites, for example carbon fiber, or metallic alloys (such as Invar).
• copper or aluminum will be more favorable.
• low density materials such as titanium or light alloys, strong enough to limit the inertial forces and associated deformations.
• Plastic materials can also be used. They can come in massive form.
• the essential advantages of the invention reside in the possibility offered to achieve an expansion, with gas working, by using moving parts without contact, and without recourse to valves.
• the flow rate of the device can be adjusted by adjusting its speed of rotation. To this end, means for adjusting the speed of rotation can be provided. Examples will be given later.
• a device according to the invention can work at slow speed. For a fixed flow, a slow speed will lead to the use of larger rooms, therefore less sensitive to miniaturization to treat low flows.
• a decisive advantage of the invention results from its ability to accept without any contraindication the formation, by expansion, of two-phase fluid, the liquid phase of which can possibly be evacuated towards the exhaust without difficulty.
• FIG. 4C Variants of the device of Figure 4A are given in Figures 4B and 4C.
• a cold coil source 35 is fixed against the flat bottom 34 of the fixed spiral.
• a cold source 37 is integrated in the walls of the fixed spiral: a fluid can therefore circulate in these walls.
• FIG. 5 represents a cryogenic expansion valve whose fixed parts are supported by a structure 50 which carries two eccentric shafts 52, 63.
• the shaft 52 centered on the bearings 53 includes an electric brake composed of a rotor 54 and a stator 55 making it possible to control the speed of rotation and to extract the expansion work towards an adaptable load receiver 56.
• the shaft 52 is provided with two eccentric axes 57 and 58 which allow, by means of the bearings 59 and 60 and an arm 62, a mechanical connection with a movable plate 61.
• the arm 62 allowing a very stable positioning and specific. The mass of this arm can, moreover, be chosen to bring the center of gravity of the mobile assembly to the desired level.
• the movable plate 61 is linked by the second eccentric shaft 63 mounted on the ball bearings 64 and 65.
• the movement of this shaft 63 is in phase with that of the shaft 52, so that the movement of the plate 61 is a translation circular, without rotation.
• All the mechanical parts described above operate at ordinary temperature in a housing 66 and a plate 67, which contain the cycle fluid 68.
• the latter can be, for example, helium at the exhaust pressure of the regulator. , close to atmospheric pressure.
• the compressed gas 69 exerts a work by setting in motion the movable spiral 70 and the plate 61, both fixed to at least one connecting element 71.
• the plate and the fixed spiral 72, carried by a tube 73, are protected from inputs external heat by an enclosure 74, which also makes it possible to evacuate the volume 75 by conventional means, not shown.
• the connecting elements 71 and the tube 73 have a hot end and a cold end. They are preferably dimensioned to be mechanically rigid, while causing minimal thermal leakage to the gas circuit to be expanded.
• An auxiliary cooling circuit 76 for example supplied with liquid nitrogen around 80 K, makes it possible to reduce thermal leaks towards the plates 70 and 72.
• regulators of the type of that of FIG. 5 can be used with gas 69 and the plates 70 and 72 working, on the first stage, around 50 at 60 Kelvin or, on the second floor, around 15 to 20 Kelvin.
• the last expansion stage where the partial liquefaction takes place, operates at around 5 to 7 Kelvin and, in this case, the auxiliary circuit 76 will preferably be supplied by the preceding stages at 50 K or 20 K.
• the movable spiral is driven in movement.
• the latter is transmitted, by the connecting elements 71, to the plate 61.
• the eccentric shafts 52, 63 in phase, make it possible to block the component of proper rotation of the movement of the movable spiral.
• the electric brake (stator 55 and rotor 54) makes it possible to control the speed of this rotation, therefore of the rotation of the axes 57, 58 and therefore the speed of the rotary translation movement of the movable spiral 70.
• deformable elements such as a network of fibers or springs, one end of each fiber or spring being fixed to the movable spiral or to its flat bottom, while the other end is linked to the fixed part of the device.
• a solution, using a deformable element, is illustrated in FIG. 6.
• the movable spiral 77 is linked, by connecting elements 78, to a movable plate 79 whose own rotation is blocked by a bellows 83.
• the latter is fixed , at its lower part, to the plate 79, and at its upper part, to a fixed part 84 of the device.
• the bellows also makes it possible to separate the atmosphere from part 86 of the enclosure, where lubricant vapors may exist, from part 87 of the enclosure reserved for high purity cycle gas.
• An eccentric shaft 80 85 fixes the circular translational travel of the plate 79. This shaft 80 is in rotation about its axis 88 ", fixed relative to the device. The axis 85 is in rotation around the fixed axis 88.
• the shaft 80 can also support the rotor 81 of an electric brake, the stator of which is designated by the reference 82.
• the device is, moreover, identical or similar to that described above in connection with FIG. 5.
• Another solution uses magnetic means, exerting forces such as translation can take place by prohibiting rotation.
• FIG. 7 The principle of this solution is illustrated in FIG. 7.
• the movable part 88 or rather the flat bottom, or from above, of the movable spiral is integral with a bar 89, either ferromagnetic, or with permanent magnetization. Both are placed in the magnetic field of an external dipole 90 whose parallel field lines fix the orientation of the part.
• the moving part 88 and its bar 89 are shown in three different positions. These parts can be linked to a plate such as the plate 79 in FIG. 6, the latter itself being guided by a single eccentric, as described above in connection with this same FIG. 6.
• FIG. 8 Another variant capable of ensuring the mechanical transmission of the circular translation movement will preferably be used for its greater compactness and the greater ease of dynamic balancing. This variant is illustrated in FIG. 8.
• the fixed base 91 supports the stator of the electric brake 92 and the hot end of a bellows 93. The latter is intended for locking in rotation of the movable spiral 94.
• the mobile part is composed of the central plate 95 connected to the mobile spiral 94 by the connecting elements 96.
• An eccentric sleeve 97 free to rotate, is centered in the base 91 by the bearing 99 and supports the central plate 95 by means of the bearing 98.
• the circular translation of the movable spiral 94 is transformed into rotation of the sleeve 97 whose speed is controlled by the electric brake 92.
• Dynamic balancing is obtained, on the one hand by a shim 100 which makes it possible to bring the center of gravity of the mobile assembly 94, 96, 95, 100 into the plane of the bearings 98 and 99 and, on the other hand, by shims 101 and 102, which make it possible to balance all the inertias applied horizontally inside the bearing 99.
• non-contact cryogenic bearings for example magnetic bearings or gas bearings
• This solution has the advantage of greater mechanical rigidity to allow better control of the respective position of the fixed and mobile spirals intended for the implementation of one invention.
• An example, illustrated in FIG. 9, uses in combination radial gas bearings and an axial magnetic stop. We could just as easily have used the opposite, or any other combination imaginable between these two known technologies.
• the example in FIG. 9 represents a helium regulator at 7 K and about 15 bars which, by expansion, will come out of the spiral towards 4.5 K, under 1 bar, in double phase, with a high proportion of liquid .
• the same solution may, let alone be used for relaxation of helium at any other temperature, such as 20 K or 60 K, or any other pressure.
• the gas to be expanded enters via line 111 at 7 Kelvin, it performs its work between the fixed spiral 112 and the movable spiral 113, before leaving as a liquid-vapor mixture via line 134.
• the mobile assembly actuated by the spiral 113, is connected by the connecting elements 115 to the plate 116 which rotates the eccentric bush 117, held in axial position by the connection 118 to the ball bearing 119 located in the hot part, at 300 K, which is braked and speed controlled by the electric brake 120.
• the plate 116 is blocked in rotation by the bellows 121, itself fixed to the hot casing 122.
• the rotation of the sleeve 117 makes it possible to maintain, on its two faces, two hydrodynamic gas bearings 123 and 124, which ensure the contactless movement inside the cryostat 125.
• This cryostat is protected from the entry of parasitic heat by the auxiliary cooling circuits 126, which hold the plate 116 of the socket 117, and the bearings 123 and 124 as well as a thermal screen 127, around 20 Kelvin and by the circuit 128, supplied around 80 K with liquid nitrogen, which is connected on screen 129.
• the axial play between the two spirals 112 and 113 is preferably strictly controlled to remain close to a few hundredths of a millimeter.
• This play measured by a cold position sensor 131, is controlled by a regulator 132 which acts on the electromagnet 133, by controlled attraction of a ferromagnetic plate 134.
• a regulator 132 acts on the electromagnet 133, by controlled attraction of a ferromagnetic plate 134.
• a regulator according to one of the embodiments described above can be used to perform a Brayton cycle, as described in the introduction to the present application, in connection with FIG. 2A.
• the invention is not limited to the production of single-stage regulators using only one pair of spirals, one being fixed and the other mobile.
• the same mechanical equipment and the same suspension set can be used for the operation of several regulators.
• the same mechanical equipment can be used to operate a three-stage regulator shown in FIG. 10, where several of the variants described have been deliberately combined in combination previously.
• the second stage works between 15 bars, 25 Kelvin (at point 143) and 1.2 bar, 15 Kelvin (at point 144).
• the third stage receives (at 145) gas at 15 bars at 7 Kelvin, which emerges (at 146) at 4.4 K as a liquid-gas mixture at 1.3 bars.
• a possible variant to make the expansion on the third stage more isothermal could be to coat the plate of the fixed spiral 171 with a condenser 180 where liquid helium could be condensed directly supplying the cold source.
• the three mobile spirals 147, 148, 149 are linked to the same shaft 150, the sections of which decrease with the temperature level.
• the shaft 150 is integral with a plate 151, at room temperature, and a plate 152, at a temperature equal to about 30 Kelvin.
• the plate 151 rotates the eccentric ring 153 mounted on the ball bearings ' 154 and 155. This ring is speed controlled by the brake 156.
• the eccentric ring 157 is held in position by a vertical magnetic stop 158. It is centered radially by two hydrodynamic gas bearings 159 and 160 which could just as easily be replaced by magnetic bearings, either with permanent magnets or with superconductors, d '' a nature to be defined according to the temperature level.
• the fixed spirals 171, 172 and 173 are integral with a casing 174 which will be isolated by a vacuum enclosure (of which the primer 175 has only been sketched without representing the pumping means).
• cryogenic circuit 178 separates the cryogenic circuit from the casing 179 which can either operate at a different pressure, or contain lubricant vapors if bearings 154 and 155 are greased.
• the bellows 176, 177 and 178 also contribute to fixing in rotation the movable assembly integral with the plates 151 and 152 and the shaft 150 to control the desired movement of circular translation.
• the example was given of a three-stage regulator for carrying out a Claude cycle. It is possible to make a regulator with a different number of stages (either two, or a number N> 3). Likewise, it is possible to use any combination of the various embodiments set out above.
• the respective position of the fixed and mobile spirals must preferably be able to be adjusted precisely, in order to limit the clearances both in the axial direction and in the radial direction.
• the adjustment means used remain entirely conventional and have not been shown to avoid weighing down the illustrations.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Geometry (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Rotary Pumps (AREA)

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• 1995
  • 1995-07-17 FR FR9508608A patent/FR2736999B1/fr not_active Expired - Fee Related
• 1996
  • 1996-07-16 EP EP96925790A patent/EP0839258A1/de not_active Withdrawn
  • 1996-07-16 WO PCT/FR1996/001102 patent/WO1997004215A1/fr not_active Application Discontinuation
  • 1996-07-16 JP JP9506349A patent/JPH11509597A/ja not_active Ceased
• 1997
  • 1997-02-06 EP EP02077846A patent/EP1251278A3/de not_active Withdrawn

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